Refillable cartridge fuse



Mar. 6, 1923.

REFI

Filed Feb. 28,

1,447,798 C. T. MCDONAL LLABLE CARTRIDGE FUSE- Patented Mar. 6, 1923.

UNITED STATES ,PATENT OFFICE.

CLARENCE T. MCDONALD, OF CHICAGO, ILLINOIS, ASSIGNOR TO CHICAGO FUSE MFG. C0., OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

REFILLABLE CARTRIDGE FUSE.

Application filed February 28, 1918.

useful Improvements in Refillable Cartridge Fuses, of which the following is a specificaf.

tion.

The invention relates to cartridge fuses-of the type generally known as rellable fuses in which the fuse element or link may'be readily replaced by the user whenl disrupted or blown and the objects of the invention are to improve the construction of fuses of this character; to provide a fuse which will prevent the melted `metal of the fuse element from clogging or interfering with the fuse-supporting means or the clamping means; which comprises separable complementary parts forming between them an opening to receive the fuse element so that said opening will always be accessible for removing and x replacin said element; by which aninvariable posltion of the fuse element in the shell will be insured; and which will prevent twisting of the fuse element when the threaded clamping element is turned up against the end thereof; and to produce a fuse which is very durable, simple and convenient to refill.

The ob'ects of the invention thus generally stated, together with other and ancillary advantages, may be attained by the construction and arrangement illustrated in the accompanving drawings forming part hereof, in which Flg. 1 is a perspective viewof one form of fuse embodying my invention, one end of the fuse being disassembled to show ythe relation of parts. Fig. 2is a fragmental axial sectional view of the same form of fuse. Fig. 8 is a transverse section on line 3 3 of Fig. 2. Fig. 4 is a fragmental axial sectional View through one end of a somewhat different form of fuse embodying my invention. Fig. 5 is a transverse section on line 5-5 of Fi 4. Figs Gand 7 are respectively side an edge elevations of an'alter-` native form of disk.

The fuse com rises a casing formed by means of a tubu ar shell 1 andmetallic end members or heads 2 fixed thereon and partially closing the ends of the casing; metallic plates or segmental disks 3 which form together with the heads 2 complete closures for the ends of the casing except for an elon- Serial No. 219,597.

gated opening formed between each end member and its corresponding disk; a fuse link 4 extending through the casingwith lts ends passing through the openings at opposite ends of the casing; and caps 5 or plugs 5 for clamping the ends of the fuse link 1n position upon the outer surfaces of the segmental disks.

The shell l of the casing is made of the usual lnsulating material, and each of the `heads 2 comprises an annular portion 2'L which is threaded or otherwise firmly secured upon one end of said shell, and a segmental wall or web portion 2b for partially closing the end of the casing. Said segmental webs at oplposite ends of the' casing extend transverse y of the annular portions 2"L inwardly toward the centers cthereof, and the inner edges are formed straight and may, if desired, be disposed in thel same longitudinal plane near the diametrical centerof the caslng. V

The segmental disks 3 or 3 which are arranged to complement or cooperate with4 the segmental webs 2b of the heads 2 to close the ends of the casing are also formed with a straight inner edge and are made o such size that the edges form, together with the edgesqf the webs 2", straight-edged openings 6 so that the ends of the fuse link may be passed therethrou h and bent over upon the outer surfaces o the disks. The bentover ends of the fuse link thus serve to hold the disks in position until the parts can be finally clamped together by means of the end caps 5 or plugs 5.

As shown in Figs. 1 to 3, the caps 5 are of ordinary construction having peripheral fianges or skirts arranged to be externally threaded -upon the heads 2, the annular rtions 2 of said heads being reduced at tligir outer ends so that the peripheries of the heads and caps are flush. In this form of fuse, the disks 3 rest upon the outer ends of the heads 2,v and, in order to form the opentation of the disks withy reference to the casing, or if desired each disk may be probeen bentvupon the outer surfaces of the Vof in the insulating sleeve.

disks and the end caps tightened upon the heads 2, the parts will have been firmly clamped together with the fuse ends in .direct electrical contact with the heads and caps. The bosses 8 and flange ll prevent rotation, or'displacement of the disks so that no twisting or distortion of the fuse can occur.

In the form of fuse shown in Figs. 4 and 5, the web portion 2b of each head 2 is spaced within the end of the annular portion 2a thereof which is internally threaded to receive the screw-threaded plug 5', the plug being provided with a groove 9 for the reception of a screw driver. ln forming the web portion 2b of this type of fuse, the straight edge of the web which forms one wall of' the elongated opening 6 for each end of the fuse linkV is made somewhat shorter than the corresponding interior dimension of the annular portion of the head, and an arcuate flange or supporting ledge l0 for the outer edges of the segmental disk 3 is provided upon the inner periphery of the annular portion of the head 2,'extending from one end of Athe web 2b tothe other. The portions of the ledge 10 at the ends of the web thus serve to restrict the opening 6 to a length corresponding to the width of the fuse link, and also to provide a shoulder for the disk to bear against.

ln ,some of the fuses of the prior art, the fuse element is supported at each end by a circular washer having a slot running inwardly from its periphery to receive one end of said fuse element,r and this washer is clamped directly against the lend of the insulating sleeve (such as is here shown at l) by means ofa metallic cap which is threaded vdirectly onto said insulating sleeve, there being no metallic head (such assis here shown at 2.) A. fuse constructed in accordance with my invention has many inherent advantages over such prior constructions. In the manufacture of the fuse, the metallic heads 2 may be permanently xed on the ends of the insulating sleeve 1 so' that the webs 2b of said heads `will be in invariable position which will not be altered by the user in refilling the fuse. Perfect position- 'ing of the fuse is'thus always insured.' The threads to receive the clamping member 5 or 5 which is removed and replaced at every fuse renewal are in the metallic head instead This sleeve is usually made of fibrous material andthe threads therein are more or less easily worn out and cut by the repeated removal and replacement of the cap. The threads may even wear down to such an extent that the cap is insecurely held on the sleeve so that it is dangerous when the fuse blows because the high pressure in the fuse may blow the cap off and injure a bystander.

By providing the webbed heads 2 which are permanently fixed on the sleeve, the disks 3--3 are held in definite position by reason of the abutting relation of the disks or the fuse element tothe webs, so that no twisting of the fuse element can be caused by the frictional engagement ,of the cap 5 or plug 5 when the cap or plug is being v.turned up against the fuse end. Furthermore, the ends of the fuse are firmly clamped between metallic faces so that shrinkage or variation of the fibre tube l will have no effect, and good electrical contact between the fuse element and terminal parts is always insured. Y

With some of the fuses heretofore known difliculty has been experienced on account of -the fact that when the fuse element is disrupted the melted part thereof' within the shell is forced outward by the pressure, and passing through the openings in the endclosing means becomes lodged in such openings and in the screw threads for the clamping cap or the like and interferes with the operation of the parts. In the type of washer which has a slot running inward from its periphery to receive the fuse element, it has been found difficult ofttimes to remove the fuse element from the washer after 1t blows and to lnsert a new fuse element on account of' the plugging or clogging of the slot by the melted metal. In some instances the nuisance of removing and replacing the fuse element has been so great that the user would intentionally break off a portion of the washer at one side of the slot so as to provide a more readily accessible support for the fuse. After such piece of the washer was broken ofi", the washer fell short of completely closing the end of the shellso that at the next disruption of the fuse the melted metal would escape in greater quantities through the larger sized opening and clogthe threads of the cap and other parts to a greater extent.

My construction entirely eliminates these difficulties by preventing the melted rfuse material from getting through the opening which the strip occupies and by nullifying any bad effect ot' the melted metal adhering to the inner sides of the end closing means or partially entering the slots through which the fuse element passes. A washer having a flange 11, as shown in Figs. 6 and 7, is especially effective for this 'purpose because it provides (in conjunction with the web 2") a slot of considerable depth. the fact .that the web 2b is integral with the head 2 and the slot for the fuse is formed By reason of' between such web and the separate disk, a fuse-receiving slot is provided which opens up when the disk is removed so that it is always easy to remove the blown fuse element from the slot and replace a new fuse element therein. Furthermore, the provision of the segmental web on theC head and the complementary segmental washer separate therefrom has the advantage of forming a slot which has straight edges at both sides so that the fuse element snugly fits the slot and prevents any melted metal from escaping from the interior of the shell.

As will be noted from an inspection of Figs. 3 and 5 the slot defined by the opposed straight edges of the web l2" and disk 3 or 3 occupies the relation of'v a chord to a circle defined by the periphery of the head 2. Preferably the disk 3 or 3 comprises the larger segment ofsuch circle and the web 2* the smaller segment so that when .the disk is removed for renewal of the fusible element, a relatively large opening will be left through which the new fusible element may be readily inserted without any danger of bending or cracking the element which might affect its calibration. When the fusible element has been inserted through both heads the disk 3 or 3 may be very easily put in place to close the remainder of the opening through the head.

I claim as my invention:

l. A refillable cartridge fuse having, in combination, a tubular insulating shell, a

rigid one-piece tubular metallic head 'fixed to one end of said shell :and having screw threads to receive a clamping -\member, a clamping member threaded to removably engage the threads of said head and having a clamping wall perpendicular to the axis of said head, a freely removable disk at the inner side of and parallel to said clamping' wall, said disk being arranged to abut at one side against a rigid integral part of said head, a fusible strip in'said shell having one vend bent to extend between said disk and `said clamping wall, whereby when the clamping member is turned up the end of the fusible strip will be clamped between said clamping wall and said disk, and the disk will be forced against said rigid part of the head, and an inwardly projecting web integral with said head lying in a plane parallel to said disk and clamping wall and having a straight inner edge, said disk having a f. complementary straight edge positioned close to and' coacting with said straight edge on the web to form a narrow slot through which said `fusible strip extends with a relatively snug lit.

2. A refillable cartridge fuse having,` in combination, a tubular insulating shell, a onefpiece rigid metallic head fixed to one end of said shell and having a. large opening through which a fusible element may be inrable parts one of which is integral withsaid headfand the other of which is freely removable, said two parts being arranged in juxtaposition and having opposed straight edges defining a narrow slot through which said fuse element extends with a relatively snug it, and a clamping element having a threaded engagement with said head and arranged to clamp the end of said fusible element and said removable part.

3. A reillable cartridge fuse having, in combination, a tubular insulating shell, a metallic .head fixed to one end of said shell and being threaded at its free ends to receive a clamping member, a clamping member threaded to engage said head, said head having an opening therethrough with a straight-edged wall defining one side of the opening, a flat fuse strip passing through said shell and the opening in said head and lying adjacent to the straight-edged wall, and a freely removable transverse disk arranged to close said opening and having a straight edge `positioned adjacent to the straight edge of said wall to define a narrow slot through which the fuse strip passes,

the end of said fuse strip being clamped between said clamping member and said disk, saiddisk havinga plurality of bosses projecting fromits inner face and arranged to cooperate with the head to prevent relative rotation of the disk and the head.

4. A refillable cartridge fuse having, in combination, a tubular insulating shell, a one-piece tubular rigidj metallic head fixed to one end of said shell and having screw threads to receive a clamping member, a readily removable 'clamping member threaded to engage the threads of said head and having a clamping wall perpendicular to the A axis of said head, a'n internally projecting transverse web integral with said head and having a straight inner edge", said Webpartially closing the passage through said head but leaving a relatively large opening through which a fusible strip may be readily inserted in assembling the fuse, a freely removable disk lying between and parallel to the planes of said web and the clamping wall of said clamping member, and a fusible strip in said shell having one end bent at an angle to extend between said disk and said clamping Wall. to be clamped thereby, said disk abutting at its other side against a rigid integral part of the head, and said disk having a straight edge which coa-cts with the straight edge of said web to define .a narrow slot through which said fusible strip extends with a relatively snug fit.

5. Ay reillable cartridge Juse having, in

one end to fit the threaded end of the shell and also exteriorly threaded and reduced in diameter at its other end, a removable cap having a peripheral flange internally threaded to receive the reduced end of said head, the peripheries of the cap and head being flush with each other, a freely removable disk at the inner side of said cap and abutting against the outer end face of said head, said disk having a straight edge, a fusible element extending through said shell and having one end bent at an angle to extend between the end wall of said cap and the said disk and be clamped thereby, and a transverse web integral with said head and lying in a plane flush with the outer end of said head and immediately adjacent to said disk, said web having a straight inner edge Which coacts Withthe straight edge of said disk to form a narrow slot through which said fusible element passes with a relatively snug fit. j

6. A refillable cartridge fuse having, in combination, a tubular insulating shell, a one-'piece rigid tubular lmetallic head fixed to one end of the shell and threaded to engage with a clamping member, a threaded clamping member adapted to removably engage the said head, a freely removable transverse disk positioned at the inner side of said clamping member y.and abutting against a rigid integral part of said head, said disk havinga straight edge, and a fusible element extending through said shell and having one end bent over said straight edge to ex- `tend between said clamping member and said disk and be clamped thereby, said head having a transverse wall integral therewith lying in a plane parallel and immediately adjacent to the inner side of said disk, said wall having a straight edge which coacts with the straight edge of said disk to form a narrow slot through which said fusible element passes.

7. A refillable cartridge fuse having, in combination, a casing having a transverse web portion partiallyuc-losing one end., a disk, a fuse element having one end passing` between said web portion and said disk, said disk having means projectinglongitudinally into the casing and serving to prevent relative rotation of the disk, and means for clamping the parts together.

8. A reillable cartridge fuse having, in combination, a tubular insmlating shell, a one-piece tubular metallic head fixed to one end of said shell and having at its extreme outer end an integral transverse internally projecting web with a straight edge, a removable disk having a straight edge and arranged to coact with said web to form a narrow slot, a flat fusible strip passing through said slot and having one end bent over the straight edge of the disk to lie along the outer face of the disk, and a cap having Laa'mee a skirt in threaded engagement with said head to clamp said strip and said disk to the head.

9. A refillable cartridge fuse having, in combination, a tubular insulating shell, a one-piece tubular metallic head fixed to one end of said shell and exteriorly threaded, a removable cap having a peripheral flange interiorly threaded to engage said head, a freely removable disk at the inner side of said cap and abutting against the outer end face of said head, said disk having a straight edge, a fusible element in said shell having one end bent over said straight edge to extend between said cap and said disk and be clamped thereby, and a transverse web integral with said head and lying in a plane flush with the outer end of said head im.- mediately adjacent to said disk, said web having a straight edge which coacts with the straight edgeof said rdisk to form a narrow slot through which `.said fusible elementv passes with a relatively snug fit.

10. In a reiillable cartridge fuse a tubular body havingl a. metallic head 'provided with an integral inwardly extending portion, av

fuse element, and a member having means projecting longitudinally into the head and arranged to co-operate with said" inwardly extending portion of the'head toposition the fuse element relative thereto.

ll. vln a relillable cartridge fuse a tubular body having a metallic head yprovided with an integral inwardly extending web, a fuse element, and a disk having a part projecting longitudinally into the head and forming in conjunction with the web ay slot of substantial depth for receiving said fuse element.v

12. In a refillable cartridge fuse, a casing, means partially closing one end of the casing, a fuse element, and a disk having al part projecting longitudinally into the casing between which part and said means the fuse element passes, said disk and fuse element serving to completely close the opening left bysaid means.

13. A refillable cartridge fuse having, in combination, a tubular insulating shell, a one-piece tubular metallic head fixed to one end of said shell and exteriorly threaded, a removable cap having a peripheral flange interiorily threaded to engager the threaded portion of said head, the head having at its extreme outer end an integral transverse internally-projecting web with a ystraight edge partially closing the opening through said head, a freely removable disk abutting against said outer end of the head and having a straight edge which coacts with the straight edge on said web to form a narrowl slot, means'to preventy relative rotation of the disk and head, and a fusible strip in the shell passing through said slot and having one end bent to lie between said disk allergies and the end wall of said cap, whereby the strip will be clamped between the disk and the cap, and the disk will be clamped against the head.

Y14. In a refillable cartridge fuse, in combination, a casing, a one-piece tubular metallic head threaded on the end of said casing, an integral inwardly projecting transverse web on said tubular head, a removable disk, adjacent -to said web and co-opera'ting therewith to form a complete closure for the end of said casing, except for a narrow straight slot, a fuse element passing through said slotand having its end portion overlying said disk, said disk having aprojection cooperating with said head to prevent relative rotation of the Jdisk and head, and clamping means engaging the metal of said tubular head for clamping the end of said fuse element and said disk.

15. In a refillable cartridge fuse, in combination, a tubular head, an integral inwardly projecting transverse web on said head, a removable disk cooperating with said web to deine a narrow straight slot between their adjacent edges, means lto prevent relative rotation of the disk and head, a 'fuse element passing through said slot and having its end portion overlying said disk, and means engaging said tubular head for clamping said disk and fuse element.

16. A reillable cartridge fuse having,

vin combination, a 'tubular insulating shell having a threaded end, a one-piece tubular metallic head having a screw-threaded engagement with the shell and also threaded to engage with a clamping member, a threaded clamping member adapted removably to engage the said head, areely removable disk positioned transversely a't the inner side of said clamping .member and hav' of a. straight edge, and a transverse web i tegral with said head and lying in a plane immediately adjacent to said disk, said web having a straight inner edge which extends parallel with and adjacent to the straight edge of said disk, and a fusible element extending through said shell and past said web and having oneV end bent at an angle over the straight edge of the disk -to extend between said clamping members and said disk and be clamped thereby.

17. A refillable cartridge fuse having, in combination, a tubular insulating shell having a threaded end, a one-piece tubular metallic head having a screw-threaded engagement with the shell and also threaded to engage with a clamping member, a threaded clamping member adapted removably to engage the said head, a freely removable disk positioned 'transversely at the inner side of said clamping member and having a straight edge, and a fusible element extending through said shell and having one end bent at an angle over the straight edge of the disk to extend between said clamping member and said disk and be clamped thereby, Said disk having a plurality of bosses projecting from itsA inner face and arranged to cooperate with the head to prevent transverse sliding movement of the disk upon the head.

In testimonywhereof, I have hereunto set my hand.

CLARENCE T. MGDONALD. 

